The goal of this project is to study the biosynthesis and inactivation of prostaglandins by the lung and other tissues. The effects of environmental agents on pulmonary transport and metabolism of prostaglandins are being investigated, and these effects are being related to pulmonary toxicity and damage. We have compared the formation of PGs from AA and PGH2 by a pulmonary tissue obtained from humans and animals. Rat lung was more similar to human lung in the kind of PG's produced. Guinea pig lung was least like human lung in PG biosynthesis. The major AA metabolite from human lung was a HFA. Preliminary results indicate that the HFA may be 5,12-diHETE. In addition, we used ESP method to study the initial steps in the formation of PG's from AA.